MetadataHelper

import { MetaAttributeAllowedCallback } from "html-validate";

export interface MetadataHelper {
  allowedIfAttributeIsPresent(...attr: string[]): MetaAttributeAllowedCallback;
  allowedIfAttributeIsAbsent(...attr: string[]): MetaAttributeAllowedCallback;
  allowedIfAttributeHasValue(
    attr: string,
    value: string[],
    options?: { defaultValue?: string | null },
  ): MetaAttributeAllowedCallback;
  allowedIfParentIsPresent(...tags: string[]): MetaAttributeAllowedCallback;
}

These functions are exported as metadataHelper and can be used when writing element metadata:

import { metadataHelper } from "html-validate";

const { allowedIfAttributeIsPresent } = metadataHelper;

allowedIfAttributeIsPresent

Returns an error if another attribute is omitted, i.e. it requires another attribute to be present to pass.

import { defineMetadata, metadataHelper } from "html-validate";

const { allowedIfAttributeIsPresent } = metadataHelper;

export default defineMetadata({
  "custom-element": {
    attributes: {
      foo: {
        /* will be allowed if bar or baz is also present */
        allowed: allowedIfAttributeIsPresent("bar", "baz"),
      },
    },
  },
});

allowedIfAttributeIsAbsent

Returns an error if another attribute is present, i.e. it requires another attribute to be omitted to pass.

import { defineMetadata, metadataHelper } from "html-validate";

const { allowedIfAttributeIsAbsent } = metadataHelper;

export default defineMetadata({
  "custom-element": {
    attributes: {
      foo: {
        /* will be allowed only if both bar or baz is omitted */
        allowed: allowedIfAttributeIsAbsent("bar", "baz"),
      },
    },
  },
});

allowedIfAttributeHasValue

Returns an error if another attribute does not have one of the listed values.

import { defineMetadata, metadataHelper } from "html-validate";

const { allowedIfAttributeHasValue } = metadataHelper;

export default defineMetadata({
  "custom-element": {
    attributes: {
      foo: {
        /* will be allowed only if "type" attribute is set to "foo" or "bar", with the default being "foo" */
        allowed: allowedIfAttributeHasValue("type", ["foo", "bar"], { defaultValue: "foo" }),
      },
    },
  },
});

allowedIfParentIsPresent

Returns an error if the node doesn't have any of the given elements as parent.

import { defineMetadata, metadataHelper } from "html-validate";

const { allowedIfParentIsPresent } = metadataHelper;

export default defineMetadata({
  "custom-element": {
    attributes: {
      foo: {
        /* will be allowed only if <custom-element> has a <other-element> as ancestor  */
        allowed: allowedIfParentIsPresent("other-element"),
      },
    },
  },
});